1. Field of the Invention
The present invention is directed to the design of optical systems.
2. Background Art
The types of optical surfaces available during the optical design process limit the performance of an optical system. Typically, spherical and specific kinds of aspheric surfaces are used when designing an optical system. Incorporating aspheric surfaces in a design is important because they add extra degrees of freedom during the design process that enable more aberrations to be corrected with fewer elements, as compared to an optical system with just spherical surfaces. However, the level to which aberrations can be corrected depends on the specific types of aspheric surfaces available in the optical design process. For example, the critical dimension, overlay and usable depth of focus capabilities of lithography tools are influenced by the aspheric surfaces and by design optimization routines available to optical designers and engineers.
Optimization algorithms provided in commercially available optical design tools are also limited by the optical surfaces available during design. One limiting factor is the cost to implement the optimization algorithms. The optimization algorithms currently available in optical design programs use multiple (spherical and aspherical) optical elements to correct aberrations, as mentioned above. According to these conventional algorithms, the number of optical elements needed to produce an acceptable image quality is often cost-prohibitive.
Therefore, what is needed is an improved optical design algorithm.